Virtual Lab for Online Cyber Security Education

In this paper, the authors describe their experience of designing a virtual lab architecture capable of potentially providing thousands of students with a hands-on learning experience in support of an online educational offering. The authors discuss alternative approaches of designing a virtual lab and address the criteria in selecting the optimal deployment method. The authors suggest that virtualization offers a significant instructional advantage in delivering a cost effective and flexible hands-on learning experience

Diffusion profile of macromolecules within and between human skin layers for (trans)dermal drug delivery

Delivering a drug into and through the skin is of interest as the skin can act as an alternative drug administration route for oral delivery. The development of new delivery methods, such as microneedles, makes it possible to not only deliver small molecules into the skin, which are able to pass the outer layer of the skin in therapeutic amounts, but also macromolecules. To provide insight into the administration of these molecules into the skin, the aim of this study was to assess the transport of macromolecules within and between its various layers. The diffusion coefficients in the epidermis and several locations in the papillary and reticular dermis were determined for fluorescein dextran of 40 and 500 kDa using a combination of fluorescent recovery after photobleaching experiments and finite element analysis. The diffusion coefficient was significantly higher for 40 kDa than 500 kDa dextran, with median values of 23 and 9 µm2/s in the dermis, respectively. The values only marginally varied within and between papillary and reticular dermis. For the 40 kDa dextran, the diffusion coefficient in the epidermis was twice as low as in the dermis layers. The adopted method may be used for other macromolecules, which are of interest for dermal and transdermal drug delivery. The knowledge about diffusion in the skin is useful to optimize (trans)dermal drug delivery systems to target specific layers or cells in the human skin

The Role of Matrix Composition and Age in Solute Diffusion within Articular Cartilage

Solute diffusion is critical to maintenance of cellular function and matrix integrity in articular cartilage. Nutrient deficiency due to transport limitations is thought to be one of the causes of the pathological degeneration of the cartilage tissue. Thus, a study of diffusion within cartilage will lead to a better understanding of the causes of cartilage degeneration. To accurately estimate diffusion coefficients in cartilage and other hydrated medium, we developed a finite-element based method, the Direct Diffusion Simulation Parameter Estimation method (DDSPE), to be used for quantitative determination of solute diffusivities from Fluorescence Recovery After Photobleaching data. Analyses of simulated and experimental FRAP data demonstrated that this method was more accurate than existing analytical methods, including having a low sensitivity to variations in the spot radius. Subsequently, the roles of extracellular matrix (ECM) composition and tissue orientation in solute diffusion within immature bovine cartilage were explored. Diffusivities were measured through the cartilage depth and in two different orientations (radial and transverse). Diffusivities were then correlated with ECM components. Matrix water content was found to be the best predictor of solute diffusion rates in immature cartilage. Although no specific experiments were done to measure the effect of structure, our results suggested that matrix structure did indeed modulate transport. Diffusional anisotropy, defined as the ratio of the diffusivities in both orientations, was observed to be significant in all the immature cartilage zones. As a consequence, the differences in solute diffusion between immature and mature bovine cartilage were investigated. Diffusion rates and diffusional anisotropy decreased in the mature cartilage superficial zone. The decrease in diffusivities observed in mature cartilage suggests that there may be a reduction in nutrient and growth factor supply to the cells. Nevertheless, healthy adult cartilage can still maintain its normal function even with a reduction in solute diffusion rates as nutrient diffusion distances are shorter in mature cartilage. However, any disruption in the mechanical or biological environment could cause an imbalance in tissue homeostasis, which when combined with decreased diffusivities, could trigger matrix degeneration. Thus, decreased diffusivity may be a necessary but not a sufficient prerequisite of matrix degeneration.Ph.D.Committee Chair: Levenston, Marc; Committee Member: Garcia, Andres; Committee Member: Koros, William; Committee Member: Sambanis, Athanassios; Committee Member: Temenoff, Johnna; Committee Member: Vidakovic, Bran

Prediction of cartilage compressive modulus using multiexponential analysis of T[subscript 2] relaxation data and support vector regression

Evaluation of mechanical characteristics of cartilage by magnetic resonance imaging would provide a noninvasive measure of tissue quality both for tissue engineering and when monitoring clinical response to therapeutic interventions for cartilage degradation. We use results from multiexponential transverse relaxation analysis to predict equilibrium and dynamic stiffness of control and degraded bovine nasal cartilage, a biochemical model for articular cartilage. Sulfated glycosaminoglycan concentration/wet weight (ww) and equilibrium and dynamic stiffness decreased with degradation from 103.6 ± 37.0 µg/mg ww, 1.71 ± 1.10 MPa and 15.3 ± 6.7 MPa in controls to 8.25 ± 2.4 µg/mg ww, 0.015 ± 0.006 MPa and 0.89 ± 0.25MPa, respectively, in severely degraded explants. Magnetic resonance measurements were performed on cartilage explants at 4 °C in a 9.4 T wide-bore NMR spectrometer using a Carr–Purcell–Meiboom–Gill sequence. Multiexponential T[subscript 2] analysis revealed four water compartments with T[subscript 2] values of approximately 0.14, 3, 40 and 150 ms, with corresponding weight fractions of approximately 3, 2, 4 and 91%. Correlations between weight fractions and stiffness based on conventional univariate and multiple linear regressions exhibited a maximum r[superscript 2] of 0.65, while those based on support vector regression (SVR) had a maximum r[superscript 2] value of 0.90. These results indicate that (i) compartment weight fractions derived from multiexponential analysis reflect cartilage stiffness and (ii) SVR-based multivariate regression exhibits greatly improved accuracy in predicting mechanical properties as compared with conventional regression.National Institutes of Health (U.S.). Intramural Research ProgramNational Institute on Agin